In the field of sewing machines, a multi-needle sewing machine is known that forms multi-color embroidery patterns with multiple needle bars. Such multi-needle sewing machine is provided with a needle-bar case containing multiple needle bars having a sewing needle attached to their lower ends. The needle-bar case is laterally transferred to locate a given needle bar at the sewing position, i.e., the needle drop position for execution of a sewing operation. The problem often encountered in such multi-needle sewing machine was needle thread tangling. Because the sewing machine utilizes multiple needle threads drawn from multiple thread spools, the strands of loose needle threads often entangled in the absence of appropriate tension management.
One solution to overcome this problem was preventing interference of threads by passing each thread through a thin elongate tube. However this required a troublesome task of passing the threads through the thin tubes.